Popa –
Firstly, the neviim couldn’t do nevius on demand.
Whatever gave you that notion?
It certainly seems that they were able to in the story with Shaul going to Shmuel to ask where he could find his missing donkeys (I Shmuel 9).
I do think there is a big difference between the navi’s ability to know the truth about things and his ability to know the future. On the latter, I agree with you.
Secondly, who says shem and ever were neviim?
You think they would say ??? ????? ????? if they weren’t? Come on.